Telecommunication Technologies
Overview Telecommunication technology might seem like a formidable challenge, but it's quite a simple foe when it comes down to it. There's just a few things to know and you'll be ready for anything! Three basic elements of a system 9/9/10 Slide 9 *'Transmitter' **Takes information and converts it into a signal (to be transmitted) *'Medium' **Carries the signal *'Receiver' **Receives the signal and converts it back into usable information Networks and Channels *'Network' **A collection of a transmitters and receivers that support the transfer of information 9/9/10 Slide 11 *'Channel' **A division in a transmission medium so that multiple streams of information can be sent at once 9/9/10 Slide 12 Circuits *'Circuit' **A path over a medium between at least two points, between a transmitter and a receiver 9/9/10 Slide 13 **Can also refer to an electronic path used for signal transfer (an application of the general idea of a circuit) 9/9/10 Slide 14 Circuit Types *Dedicated 9/9/10 Slide 18 **Directly connects devices in a network without accessing a switch **Path is available 24/7 for use by a designated user (an individual or a company) **Available on a private or leased basis **An example of a dedicated circuit is the direct phone line from the US to Russia *Switched 9/9/10 Slide 19 **Circuit is temporarily established, at the request of a station connected to the circuit **Connected on a flexible basis through one or more switches **A switch is a device that establishes, maintains, and changed logical connections over physical circuits 9/9/10 Slide 20 *Virtual 9/9/10 Slide 21 **Refers to a logical connection (rather than a physical one) over which data from a source is passed to a destination over various real circuit configurations during one period of communication **A generalized (abstracted) form of a circuit that can be applied to many physical examples of circuits **Can be fixed (permanent) or dynamical determined at the time of transmission (switched) Measuring Capacity 9/9/10 Slide 23 *Hertz **Cycles per second of a periodic phenomena (usually a wave) **So if a wave repeats 8 times per second (that is that the waveform "restarts" 8 times in 1 second), we measure the wave to have 8 Hz *Baud 9/9/10 Slide 24 **How many signal elements are sent in 1 second **Although 8 bits are sent in the example below, we measure it as 4 baud, as the signaling element only signals 4 changes *Bps (bits per second) **How many bits are sent in 1 second **In the example below we can clearly count 8 bits sent during the 1 second period, so we measure it as 8bps or 8 bits per second. Types of Bandwidth 9/9/10 Slide 25 *Narrowband **A transmission channel with a single voice channel (usually 4kHz or less, 64kbps or less) *Wideband **A transmission channel with wider bandwidth than one voice channel (usually used to contrast narrowband) *Broadband **A transmission channel more than 64kbps, usually can also provide multiple channels of data over a single medium Analog vs. Digital *Analog 9/9/10 Slide 27 **Signal is analogous to the original information **Measured in Hz **Uses amplifier to boost signal for transmission over some distance **Pros9/9/10 Slide 28 ***Continuous flow - easy to recover ***Natural way that people create and consume signals ***Widely available **Cons ***The more information, the more bandwidth required ***Noise (excess data that contains no information) ***Insecure *Digital9/9/10 Slide 30 **Information converted to 1s and 0s (pulse signals) **Measured in bps (bits per second) **Uses repeaters to boost signal over distance **Pros9/9/10 Slide 31 ***Increased efficiency through compression ***Enhanced security ***Improved error performance, therefore higher quality **Cons ***Relatively high cost (in comparison to analog) ***Upgradeability / Scalability ***Attenuation, noise Converting Digital and Analog Signals *Modem (Modulator demodulator) 9/9/10 Slide 32 **modulated outgoing digital signals from a computer or device to analog signals **demodulated incoming analog signals and converts it into a digital signal for the digital device *Codecs **Coder/decoder 9/9/10 Slide 34 **Standardized conversion of analog signals into digital form to send on a digital circuits **Usually compresses them in order to conserve bandwidth on a transmission path [[Transmission Systems|'CONTINUE...']] [[TC201 Giga Wiki|'MENU']] References